1. Field of the Invention
The present invention is directed to a method for the making of magnetic heads in thin layers and with a planar structure. In particular, it concerns the making of the pole pieces and the gap of recording and reading heads for different applications such as computer, audio or video applications.
2. Description of the Prior Art
Depending on the types of heads, the applications and the desired performance characteristics, different technologies may be used to make the gap and the pole pieces. The patent application EP 262 028 discloses a method for making magnetic heads in thin layers and with a planar structure. This method makes it possible to obtain a narrow gap formed by a non-magnetic layer and pole pieces with a shape such that they lead to a concentration of flux in the vicinity of the gap and have a small area without protection. This method implements thin layer deposition and etching operations that are usual in the technology of integrated circuits, as well as operations for the electrolytic deposition of various magnetic layers.
However the method according to the EP 262 028 provides for the making of magnetic heads that have the following drawbacks.
The height of the pole pieces is restricted to a maximum value of about 4 to 5 .mu.m. This method therefore cannot be used for making DAT (digital audio tape) or video heads which are subjected, during operation, to a major degree of wear and tear, and therefore require the pole pieces with a greater height (of the order of 15 .rho.m).
Furthermore, the gap (or spacer) is relatively brittle. Although, the gap is mounted on a support and is of the same nature as the support, there is nevertheless a point of embrittlement at the interface between the gap and the support.
Also it is difficult to achieve perfect control over the perpendicularity of the spacer for major heights (4 to 5 .mu.m).
The fact that the gap is obtained by the deposition of a mineral material and by a method appropriate for this material results in the thickness of the gap being restricted to values ranging from 0.3 .mu.m to 2 .mu.m.